German Published Patent Application No. 38 25 138 describes a method and device for adaptively determining positioning unit. The device includes a controller for controlling the position of a quantity-determining positioning unit in a diesel gasoline engine. The device adjusts the position of the quantity-determining positioning unit to a predetermined value. This predetermined value is fed to the input of the loop controller, via a signal-forming device.
The signal-forming device can be located in a predetermined-signal line or in a branch line. The predetermined signal is combined with a signal which is dependent on the output signal from a setter.
Unfavorable loop-controller characteristics result under certain operating conditions. In particular, in the closed-loop control of friction-encumbered electromechanical positioning systems, the static or sliding friction in the system causes dynamic losses in the low-level signal, i.e., small modifications of the predetermined value. Similar problems are encountered in other positioning units, such as in a throttle-valve-control unit.
It is an object of the present invention to achieve an optimum control response under all operating conditions, in a system for controlling a positioning unit in a motor vehicle, and to improve the dynamic response of the system without decreasing the stability of the closed control loop.